Parce

- restructured standard actions, easier to combine actions
- improved default styles, added a template for new CSS styles
- added oldfashioned terminal CSS style (see parce/themes)
- parce is now fully recursion proof, there is no limit on the depth of a tree
- added toml parser
- added tex/latex parser
- added HTML parser, building on the XML parser and supporting CSS
- support \score inside \markup in LilyPond
- added the registry module, and the main find() function
- TreeBuilder.peek(start, tree) now also gets start position
- default_action can now be a dynamic item (TextItem)
- added the main maparg() helper

- added documentation with examples for bundled languages
- added ini file parser
- added mapmember and mapgroupmember rule items
- tree builder: simpler API, all types now simply use rebuild()
- tree builder: while building new tree, keep old tree intact
- tree builder: now it is possible to get fine-grained updates
- added treebuilder.peek() functionality to get a quick first part of a build

- bytext() and bymatch() are now generic "replacables", they can be used
to specify an alternative action, target or both in one go. tomatch() was not
needed anymore and is gone.
- much more replacables, all replacable items now inherit from DynamicItem,
(except for Pattern)
- make it possible to create derived lexicons, e.g. to parse here documents
- improved LilyPond and Scheme parser
- added JSON parser
- lexer resurrected, now generates an event stream, which is used by the tree
builder
- documentation improvements, more examples in doc strings

- Large improvements in theme module, MetaTheme working well
- MetaTheme can render embedded themes with their own window style
- Added formatter module to format/highlight/colorize text using a Theme
- More queries in query module, and a query evaluates to False when no results
- Smart Context.context_slices method that yields slices of nodes per-context
for every range. When processing the nodes from each slice we know they
originated in the same lexicon and language.
- Documentation improvements, better cross-linking

- Added CSS module to parse and use stylesheets, using CSS lang def
- Added theme module using CSS to assign text formats to standard actions

- Added testing using pytest
- Added CSS parser
- Improved LilyPond and Scheme parser
- Documentation added and improved
- Running `pytest-3` now also validates all languages